From UPSC perspective, the following things are important :
Prelims level : Natural satellites of various planets
Mains level : Not Much
- The International Astronomical Union’s Minor Planet Center confirmed 20 new moons orbiting Saturn, making it the planet with the most moons in our Solar System, at 82.
Moons count for various planets
- A count of the moons listed on the NASA website shows that our Solar System’s planets together have 205 confirmed moons now.
- Saturn and Jupiter, with 161 between them, account for nearly 80% of these.
- Another 20% are orbiting Uranus (27) and Neptune (14).
- Of the remaining three moons, one is Earth’s own while the other two are with Mars.
What’s so special about Saturn?
- The newly discovered moons of Saturn are about 5 km each in diameter.
- Seventeen orbit Saturn opposite to the planet’s rotation, and three in the same direction as Saturn’s rotation.
No moon for Mercury and Venus
- Mercury is so close to the Sun and its gravity that it wouldn’t be able to hold on to its own moon, NASA explains.
- Any moon would most likely crash into Mercury or maybe go into orbit around the Sun and eventually get pulled into it.
- It is not yet clear, however, why Venus does not have a moon.
About International Astronomical Union (IAU)
- The IAU is an international association of professional astronomers, at the PhD level and beyond, active in professional research and education in astronomy.
- Among other activities, it acts as the internationally recognized authority for assigning designations and names to celestial bodies (stars, planets, asteroids, etc.) and any surface features on them.
- To standardize planetary nomenclature, the IAU was assigned in 1919 the task of selecting official names for features on Solar System bodies.
- Planetary nomenclature, like terrestrial nomenclature, is a system of uniquely identifying features on the surface of a planet or natural satellite so that the features can be easily located, described, and discussed.